THE NAUTILUS. Ill 



NEW SPECIES OF AMNICOLA FROM NEW MEXICO AND UTAH. 



BY HENRY A. PILSBRY. 



Amnioola neomexicana n. sp. 



The shell is very small, minutely perforate, globose, corneous, 

 rather solid. Surface smooth, not glossy. Whorls 3, moder- 

 ately convex, the suture not deeply impressed. Aperture 

 ovate, strongly oblique, angular above. Peristome continuous, 

 the outer margin regularly arched, inner margin straight, 

 slightly thickened. Length 1.6, diam. 1.3 mm.; longest axis 

 of aperture about 1 mm. 



Socorro, New Mexico, in warm springs. Types no. 121,113 

 in the Wheatley collection, deposited in Mus. A. N. S. P. 



This species, known by many specimens, is smaller than 

 Amnicola micrococcus, with a narrow aperture, straight inner lip 

 and less impressed suture. Nearly all of the shells are eroded, 

 the spire being deeply corroded in fully adult individuals. 

 This gives an abrupt outline of the suture, in front view. 



Amnicola desert a n. sp. 



The shell is very small, perforate, broadly ovate, corneous, 

 translucent, thin ; surface glossy, very minutely marked with 

 delicate growth-lines. The outlines of the spire are convex, 

 the apex somewhat pointed. Whorls 3^, strongly convex, the 

 last more rapidly descending close to the aperture. The aper- 

 ture is ovate, somewhat oblique, angular above. Peristome 

 continuous and free from the preceding whorl. Length 2.4, 

 diam. 1.7 mm.; longest axis of aperture 1.25 mm. Length 2.2, 

 diam. 1.6 mm. 



Washington Co., Utah. Types no. 121,112, Wheatley col- 

 lection, in coll. A. N. S. P. 



This little shell resembles the larger Bythinella palomasensis, 

 from Lake Palomas in northern Chihuahua (Nautilus IX, 68, 

 Oct., 1895 ; Dall, Proc. U. S. Nat. Mus. XIX, 1897, p. 369, pi. 

 31, fig. 9). The present species is broader, and evidently old 

 individuals are smaller. The generic position is uncertain. As 

 between a short Paludestrina and a long Amnicola there is little 

 choice. 



